> The cobalamin molecules are quite large and don’t penetrate the sublingual mucosa very well.

Absolute nonsense.

Did you even bother to look for one paper on the subject? Here are a few:

https://www.scielo.org.mx/scielo.php?pid=S0034-8376202000060...

https://pubmed.ncbi.nlm.nih.gov/34871525/

https://www.proquest.com/openview/e9a25963dbc92150e420a3a847...